Energy: where it comes from and where it goes

Ages 13 to 17 Read alone · about 50 minutes

Read together

Energy cannot be created or destroyed. It changes form: chemical energy in food becomes movement and heat in your body, and electrical energy in a lamp becomes light and heat. This is the law of conservation of energy.

Most of the world's energy still comes from fossil fuels: coal, oil and gas. Burning them releases carbon dioxide. Renewable sources, such as sun, wind, water and the heat inside the Earth, do not run out. The Philippines is one of the world's leading producers of geothermal electricity, using volcanic heat.

Every energy change wastes some as heat. Efficiency is how much of the energy goes to the purpose you want. An LED bulb turns much more of its electricity into light than an old filament bulb.

Do it

1. Do a home energy audit with a grown-up: list five appliances, their power ratings in watts and how long they run each day. Estimate each one's daily energy use.
2. Compare an LED bulb and an older bulb: which uses fewer watts for the same light?
3. Draw a diagram of the energy from the sun to the food you ate today to your movement.
4. Choose one way to use less energy at home this week and track it.

Talk about it

• Where does the energy in a bowl of rice come from?
• Why is a wasted joule not truly lost?

For the grown-up

Energy choices affect cost, health and the climate. The Philippines gets part of its electricity from geothermal sources, and the International Energy Agency reports that fossil fuels still supply most of the world's energy. Talk about stewardship of creation without fear.

Mark as done

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Where this comes from

• NGSS Lead States, Next Generation Science Standards: For States, By States (National Academies Press, 2013), performance expectation HS-PS3-1 (create a computational model to calculate the change in the energy of one component in a system when the change in energy of the other components and the energy flows in and out of the system are known)
• International Energy Agency (IEA), World Energy Outlook, on the share of fossil fuels and renewables in global energy supply
• Department of Energy (Philippines), information on geothermal and renewable energy in the Philippines

Written with AI assistance and checked against the sources listed. Please read it before sharing it with a child.